Hydraulic valve



HYDRAULI G VALVE Filed OG. 14, 1927 5 Sheets-Sheet 1 Sep. E@ 93@ C. E,POWELL 'TI@ HYDRAULI C VALVE Filed Oct. 14, 1927 5 Sheets-Sheet 2 nINVENTOR QM gmx/W1 p., @@y Q. C; E. POWELL U@ HYDRAULIC VALVE Filed Oct.14, 1927 5 Sheets-*$11681*l 5 INVENTOR Patented Sept. 30, 1930 UNITEDSTATES CORPORATION F PENNSYLVANIA PATENT OFFICE CLARENCE E. POWELL, 0FMUNHALL BOROUGH, PENNSYLVANIA, ASSIGNOR TO HOME- STEAD VALVEMANUFACTURING COMPANY, 0F HOMESTEADy PENNSYLVANIA, A

HYDRAULIC VALVE Application led October 14, 1927. Serial No. 226,081.

. More particularly my present invention relates to hydraulic valvestructures wherein the valves are arranged to be opened by the pressuresin the valve passages and to be closed by pressures built up on theother sides of the valves.

Thus in the type of hydraulic valve which is shown in the drawingsmerely to illustrate a practical `application of the principles of mypresent invention, the valves are piston valves which work in cylinders,the valves being caused to close by the pressures built l up in thecylinders and to be opened by the pressures in the valve passages whenthe pressures in said cylinders are relieved.

The hydraulic uid by which the pressures are obtained for closing thevalves is admitted through restricted passageways, usually provided withadjustable throttle valves, the orifice being sometimes as small as onesixty-fourth of an inch, and such pressures are relieved, to permit thevalves to open, by a pilot valve or valves usually handoperated.

In the presentpractice these restricted passageways receive theirsupplies of hydrauhc fluid directly from the chambered interior of thevalve casing wherein the pressures are subject to material variations.

Thus in the case of an eXhaust valve in a multiple-way hydraulic valvethe pressure to close the Valve is taken from the other side of saidvalve and such pressure is frequently so low that the valve either willnot close or closes so sluggishly that there is a substantial waste ofthe hydraulic fluid and the operation of the mechanism controlled by thehydraulic valve is rendered inefficient.

Therefore one of the objects which Thavc in View is the provision ofmeans whereby the proper and uniform closing of the valves is assured.

This l accomplish by supplying the hydraulic fluid for closing thevalves from a source of uniform and sufficient pressure unaffected bythe variation of the internal pressures of the valve casing.

ln the embodiment illustrated in the accompanying drawings T have shownthis pressure supplied either by an auxiliary pipe unconnected to thevalve casing or by a pipe connected to an area of uniform pressure insaid casing such as the service pressure intake.

Again in mills and plants employing hydraulic power the fluid used isusually water pumped from a neighboring stream or river, and it is notpractical to pass this supply through a strainer having less thantwoeighths or three-sixteenths inch orifices. Such water usually carriesconsiderable grit and silt and also bits of dbris,and the iuid which haspassed through the hydraulic cylinders usually carries in suspensionsmall pieces of packing.

Hydraulic fluid carrying such impurities is not suitable for use in therestricted passages and throttle valves above referred to, and thereforein the present practice there inevitably occurs a clogging whichdiminishes and frequently interrupts the supply of the hydraulic fluidto be employed in closing the valves.

Therefore a second object which l have in view is to furnish to thepiston-cylinders of the valves a uniform supply of hydraulic Huid whichis free from foreign materials which tend to clog the restrictedpassageway or the throttle valves,

l accomplish this purpose by the segregation of a portion of thehydraulic fluid from the service supply and thoroughly straining it toremove the grit, silt and other foreign materials which cause thetroubles above referred to.

The amount of water to be strained is very small in proportion to theamount of water going through the main valve. Experiments on valves inactual service show that the amount of water going through the throttlevalve is only about one twentieth of one percent of that going throughthe main valve. This proportion, however, varies, in some places beingvery much less and in other cases being much greater, although nocondition can be pictured where the proportion would ever be greaterthan one percent. This, therefore, shows the feasibility of segregatingthis small, portion of the water which goes through the throttle valvesand shows how it is possible even with very small strainers to ve finelystrain this water, using mesh even as ne as one sixt -fourth of an inchor a correspondingl bas et with one-sixtyfourth inch diameter holes,oreven smaller if r uired. A

Ot er novel features of construction, and also of arrangement of partswill appear from the followin description.

For the sa e of clear'ness lof description I have illustrated theprinciples of my inven-v tion applied to well known types of fourway andthree-wa hydraulic valves, but it is to be understoo that the structureof the hydraulic valve is in itself no part of my present invention.

Referrin to the drawings, Fig. 1 is a plan view of a our-way hydraulicvalve; Fig. 2 is a. view in vertical section taken along the line 2-2 inFig. 1; Figs. 3 and 4 are views in horizontal section taken respectivelyalong the line 3-3 and 4-4 in Fig. 2; Fig. 5 is a Elanview of athree-way hydraulic valve;

ig. 6 is a sectional view taken along the line 6-6 in Fig. 5; Fig. 7 isa side elevation of the pilot valve; Fig. 8 is a sectional view takenalong the line 8-8 in Fi 7, and Fig. 9 is a sectional View. of one o thethrottle valves.

Referring to Figs. 1, 2, 3 and 4, 1 repre- A`sents a four-way hydraulicvalve casing provided with a service inlet 2 which is intended to beconnected up to the main hydraulic fluid pressure supply line. The valvecasing is also provided with two service leads 3 and 4 which areintended for connection to the opposite ends of a double-actin hydrauliccylinder not shown. The caslng is also provided with an outletconnection 5 to waste.

The valve body 1 is provided with four valve chambers extending throughthe casing and indicated at 6", 6", 6 and 6d. In chambers 6 and 6b aremounted the inlet valve and the outlet valve, res ectively, for theservice lead 3, while the in et valve and the outlet valve for theservice lead 4 are mounted in the chambers 6c and 6, respectively.

Each of the .valve chambers is provided with an upper enlargement 7 anda lower enlargement 8.

The enlargement 7 of the valve chamber 6c is connected to the inlet 2,and is also connected to the enlargement 7 of the valve seat 6 by thepassage 9. The enlargement 8 of the valve seat 6d is connected to theoutlet 5 and the enlargements 8 of the valve seats 6b and 6 areconnected by the passage 10. The enlargement 8 of valve seat 6SL and theenlargement 7 of valve seat 6 are connected by the passage 11. Likewisethe enlar ment 7 of the valve seat 6 is connected Iiy the passage 12 tothe enlargement 7 of the valve'seat 6.

The valve structures installed in the four chambers are identical, and Iwill describe in detail that mounted in chamber 6' and shown in sectionin Fig. 2.

13 represents a seat bushing mounted in the lower portion of the valvechamber 6 and extending up into the enlargement 7. The interior of thebushing is in open conimunication with the enlargement S through theports 14.. At its lower end the bushing is provided with an `axialopening 15 provided with a packing-gland 16. 17 is the valvepiston whichworks in a piston-bushing 18 held in the chamber 6'i by the annularlocknut 19. The piston carries the cup-Washers 20 and 21 separated bythe annular washer 22 and held in place at one side by the annularshoulder 23 on the piston 17 and at the other side by the annular washer24 and the cup-nut 25 screwed on a threaded portion of the piston 17. 26is the valve disc, made of compressible material and arranged, when thevalve is closed to engage and seal the inner or upper end of the bushing13. The disk is held in place on the lower end of the piston 17 betweenthe' outer sleeve 27, which is screwedon external threads on the piston,and the holder-nut 28 screwed into internal threads of the piston, thelower ends of sleeve and nut being provided with annular flanges whichhold the disk in place and are separated suiiiciently to provideclearance for the upper end of bushing 13. The sleeve 27 is providedwith spaced fingers 29 which are in sliding relation with the exteriorof the bushing 13 so as to hold the piston in proper alinement and atthe same time to permit the free passage of water between the inner endof the bushing and the disk when the valve is open. The holder-nut 28 isprovided with an axial and threaded hole in which is screwed thethreaded inner end of a guide stem 30 which extends outwardly throughthe gland 16. The upper end of the piston 17 is reduced in diameter,forming a circumferential shoulder 31 and a boss 32. 33 represents ahelical spring surrounding the boss 32, and bearing at its inner endagainst the shoulder' Bland at its outer end against the bonnet 34screwed into the threaded end of the valve chamber 6. The upper end ofthe valve chambers are ,thus cylinders for the piston valves.

It is evident that when the valve in cha1nber 6a is open and the valvein chamber 6b is l closed fluid pressure is supplied to the service lead3 and thus power may be applied to the corresponding end of adouble-actingv hydraulic cylinder. On the other hand if the valve inchamber 6a be closed and that in chamber 6b be opened, power is relievedfrom the service lead and from the corresponding end of the hydrauliccylinder. The valves in chambers 6c and 6d are correspondinglyinterposed between the service lead 4 and the 1 fluid-pressure inlet 2and between the service lead 4 and the outlet 5, respectively.

rllhus when the valves in .chambers 6a and 6d are open and the valves inchambers 6b and 6c are closed, fluid pressure is supplied to the servicelead 3 and relieved from the service lead 4, thus causing the piston totraverse the hydraulic cylinder in one direction, and when the valves 6nand 6d are closed and the valves in chambers 6b and 6c are open theHuid-pressure is relieved in service lead 3 and supplied to service lead4, thereby causing the piston to traverse the hydraulic cylinder in theopposite direction.

Thus the valves in chambers 6a and 6d must be arranged to open when thevalves in chambers 6b and 6 close, and vice versa.

'l` he valves are opened and closed by means of a remote control.

Thus the valve chambers 6 and 6d are connected above the pistons 17 tothe branched pipe which is also connected to a throttle valve 36.Likewise the valve chambers 6b and 6 above their pistons are connectedto the pipe 35a which is connected to the throttle valve 36a. rlhethrottle valves are in turn connected to an auxiliary fluid pressurepipe 37 in which'the necessary pressure is maintained and which containsa strainer 38. There are a number of elicient strainers on the market,any of which may be interposed in pipe 37. The auxiliary supply pipe 37in solid lines in Fig. l, is shown as a pipe unconnected to the valvecasing l or its intake 2, said pipe being connected to the fluidpressure service main at some convenient point, thus segregating aportion of the hydraulic fluid before the latter reaches the intake ofthe valve casing. 'lhe proper cleansing or straining of the relativelysmall supply requisite for the valve closing function may thus bereadily and economically effected without involving a like cleansing ofthe main supply which would not be commercially practical.

However, l may take the auxiliary supply of hydraulic fluid from aportion of the valve casing itself wherein the pressures are notsubjected to the variations already referred to. Thus in dotted lines inFig. 1 ll show an auxiliary supply pipe 37a provided with a strainer 38aand connecting the throttle valves 36 and 36a to the valve casing 1 atthe intake 2 where the pressure is uniform. ln such case l do not usethe pipe 37 shown in full lines.

39 represents a double acting, hand-oper ated pilot. valve whoseopposite sides are connected with the pipes 3,5 and 35a by the pipes 40and 40a, respectively.

When the pilot valve is thrown in the one direction, it closes the pipe40 and opens the pipe 40, thus permitting pressure to be built up in theupper ends or piston cylinders of the valve chambers'Gafand 6d and withthe assistance of the springs 33 causing the closing of thecorresponding valves. Simultabe built up in the piston 'cylinders of thechambers 6b and 6c, causing said valves to close.

When the pilot valve is at neutral the four valves in the body areclosed.

The throttle valves 36 and 36a are adjustable so that the rate at Whichthe hydraulic y fluid is admitted to the piston cylinders of the valvechambers may be regulated to produce a cushioning of the closing of thevalves. 'lhe relief of pressure however is through the pilot valve andthus the opening of the valves is positive and rapid. The waste pipe ofthe pilot valve is shown at 41 in Fig. 1.

Referring now to Figs. 5 and 6, wherein l illustrate the application ofmy invention to a three-way hydraulic valve, such as is employed inconnection with a single-acting hydraulic cylinder, the body l of thevalve is provided with a fluid-pressure inlet 2, a service lead 3a, anoutlet 5a, and two valve chambers 6e and 6f. The lower enlargement 8 ofthe valve chamber 6e is connected by a passage l2 with the' enlargement7 of the valve chamber 6f, and said enlargement 'i' is connected to theservice lead 3a. rl`he pressure supply 2f* is in communication with thecorresponding enlargementl 7 of the valve chamber 6e. rll`he lowerenlargement 8 of the valve chamber 6l is in communication with theoutlet 5a.

'lhus when the valve in chamber 6e is open and the valve in chamber 6fis closed pressure is supplied to the lead 3a, and, on the other hand,when the valve in chamber 6e is closed and the valve in chamber 6t isopen the pressure is relieved from the lead 3a.

rlhe upper end of the valve chamber 6e is connected by a branched pipe35b with athrottle valve 36h. The upper end of the valvechamber 6f isconnected by a branched pipe 35c with a throttle valve 36e.

rl`he pipes 35h and 35c also connect the upper ends of the valvechambers 6e and 6. respectively, to the opposite sides of the pilotvalve 39a. 43 is the waste pipe leading from said pilot valve.

The throttle valves are also connected to the branched auxiliarypressure-supply line 37b in which is interposed the strainer 38". Theauxiliary supply line 37 b shown in solid lines in Fig. 5 is unconnectedwith the valve casing, but in dotted lines I show the auxused.

It is evident that when the hand lever of the pilot valve is thrown inone direction the valve in chamber 6 is opened and the valve in chamber6 is closed, and when thrown in the opposite direction the valve inchamber 6 is closed and that in chamber 6r is opened. When the lever isat neutral both valves are closed. v

In Figs. 7 and 8 I have shown a suitable form of pilot -valve which Iprefer to emplo lyhe same is of the following character:

The valve body is provided with two parallel chambers 44 and 44b inwhich work the piston valves 45 which seat on the inner ends of thevalve bushin s 46 and are seated by the helical s rings 4-1 'which bearagainst the bonnets 48 w -ich are screwed into the threaded end of thevalve chambers. 49 represents the valve stems fixed to the piston valves45 and extending through a gland in the outer end of the bushings 46.

The bushings are ported to communicate with the circumferentialenlargement 50 of the valve chambers and said enlargements are connectedby a port 51 through the valve body.

Above the bushing 46 the valve chamber 44* is enlarged and provided witha threaded port 52 to whicn,in the case of the fourwa valve shown inFigs. 1 and 2 the pipe 40 1s connected. Likewise the valve chamber 44*is provided above the bushing with a threaded port 52a to which the pipe40a is connected. The enlargements 50 of the valve chambers 44l arerovided with threaded ports 53 to one of wlliich the waste pipe 41 isconnected. The other port 53 may be plugged as shown at 54.

The outer ends of the valve stems 49 are provided with Contact rollers55.

56 is an inverted yoke whose legs are pivotally mounted on the ends of abolt 57 exten-:ling throu h a sleeve 58 integral with the valve body.aid yoke has a hand lever 59 fixedly attached thereto, which leverextends u Wardly and may be swung in a segment of) a circle between thelimiting projections 59 on the valve body.

'I'lie yoke has secured thereto, as by bolts, the cam 60, indicated bydotted lines in Fig. 8, whose contact surface is in the form of anupwardly convexed arc and which is so disposed that when the hand lever59 is in its intermediate position shown in the drawings the valve stemsare projected outward and the valves are both closed. lVhen the handlever is swung to the left in Fig. 8, the cam enga es the roller of thestem of the valve in c amber 44", thus opening said valve while the`valve in chamber 44" remains closed. On the contrary, if the hand leverbe swung to the right in Fig. 8, the valve in chamber 44h is opened andthe valve in chamber 44l remains closed.

VVh'en the pilot valve is connected up with v the three-way hydraulicvalve illustrated in Figs. 3 and 4, the pipe 35b is connected to theport 52 and the pipe 35 with the port 52,

In Fig. 9 I have shown a Vertical section of the throttle valve which Iprefer to use.

Thus 61 is the valve body having an end port 62 to which is connectedthe auxiliary pressure supply line 37 in Figs. 1 and 2 and 37b in Figs.3 and 4. The other end of the body 61 is provided with a circularthreaded hole 63, and 64 is a lateral port adjacent thereto. In Figs. 1and 2 the pipe 35 or 35"L is connected to the port 64 while in Figs. 5and 6 the connection is with pipe 35b or 35.

Intermediate of the ports 62 and 64 the body 61 is provided with atransversely disposed web 65 which is provided with a circular, threadedhole 66 which is axially alined with hole 63. 67 represents a seatsleeve which is exteriorly threaded and screwed into the hole 66. Theupper bore of the sleeve 67 is of slightly greater diameter than itslower bore, thus forming between the bores the internal shoulder 68. Thelower bore is threaded. The valveplug 69 has a reduced and threaded endportion which screws into the threaded lower bore of the sleeve and itsupper portion is cylindrical and has a sliding fit with the upper boreof the sleeve. The valve plughas integral therewith a stem 70 whichextends up through the packing gland 71 which is carried by the packingbox nut 72 screwed into the threaded hole 63. The outer end of the stemis squared for the application of a tool or handle, and 73 is a bonnetwhich is screwed onto the exteriorly threaded end of the valve body toinclose the stem and packing.

The plug 69 is provided with a bore 74 extending inwardly from the loweror outer end of the plug, and 75 is a longitudinally slotted portthrough the wall of the plug connecting the bore to the exterior of theplug. The port is so located that when the plug is screwed completelydown into the sleeve 67, the wall of the sleeve completely seals theport so that no fluid pressure may pass through the valve from the port62 to the port 64. By unscrewing the plug, any desired degree or all ofthe port 75 may be exposed and thus admitting the fluid pressure pastthe web 65.

It is thus evidentthat by properly adj usting the plug in the sleeve thefluid supply may be throttled or regulated to that desired, and therebycushioning the closing of the valves to exactiy the desired degree.

It is evident from the foregoing that the closing of the valves isaccomplished by the building up of a differential pressure effectiveonthe upper or inner end of the movable valve member until this pressureplus the expansive power of the helical spring is able to overcome thepressure on the opposit'eor seating side of the valve member. Thus theclosing of the valve may be cushioned by regulating the capacity of thethrottle valve to avoid jarring or hammering upon the closing of a valveor valves.

Moreover it is obvious that the opening of the valve is positive, in somuch as the throwing of the pilot valve in the proper direction relievesto Waste the pressure accumulated above the valve piston, permitting thepressure on the opposite side of the piston to promptly open the valve.

Again the use of an auxiliary fluid pres: sure supply for providingpressure for closing the valves enables me to use the proper pressurefor that purpose regardless of the pressure used in the service supplyline of the hydraulic valve.

lt is obvious that as the pressure, for closing the valves, is suppliedthrough the adjustable throttle valves from an auxiliary pressure supplyline, Whose pressure is unaffected by variation of pressure which occursin the chambers of the hydraulic valve, there is no lag or uncertaintyin the closing action of the valves, such as is characteristic ofhydraulic valves wherein the pressure employed to close the valve is notconstant.

Moreover l am able to strain the Water or other fluid therein Withoutstraining the service supply for the hydraulic valve, and am thus ableto avoid the clogging of the restricted passages and the throttle valvesand the impairment of the accuracy of their functioning.

What l desire to claim is l. ln a hydraulic valve, the combination of avalve body having a chambered interior for the passage of the hydraulicfluid, a valve seat in said valve body in the path of the hydraulicfluid, a movable valve member to close said seat, the valve member beingarranged to move to close in the same direction as the travel of thehydraulic fluid through the valve seat When the valve member is in itsopen position, said valve member being arranged to be opened by thepressure of the hydraulic fluid at said valve seat and to be closed bythe pressure of hydraulic fluid effective against the opposite end ofthe valve member, a hydraulic liuid supply for closing the valveindependentof the pressure variations of the valve seat, a throttlevalve in said independent hydraulic fluid supply, and a. relief valve insaid independent hydraulic fluid supply.

2. ln a hydraulic valve, the combination of a valve body having achambered interior for the passage of the hydraulic fluid, a valve seatin said valve body in the path of the hydraulic iiuid, a movable valvemember to close said seat, the valve member' being arranged to move toclose in the same direction as the travel of the hydraulic fluid throughthe valve seat when the valve member is in its open position, said valvemember being arranged to be opened by the pressure of the hydraulicfluid at said valve seat and to be closed by the pressure of hydraulicHuid effective against the opposite end of' the valve member, ahydraulic fluid supply for closing the valve4 independent of thepressure variations at the valve seat, means for cleansing saidhydraulic fluid supply from impurities, a throttle valve in saidindependent hydraulic fluid supply, and a relief valve in saidindependent hydraulic fluid supply.

3. ln a hydraulic valve, the combination of a valve body having achambered in terior for the passage of the hydraulic fluid, a valve seatin said valve body in the path of the hydraulic fluid, a movable valvemember to close said seat, the valve member being arranged to move toclose in the same direction as the travel of the hydraulic fluid throughthe valve seat When the valve member is in its open position, said valvemember being arranged to be opened by the pressure of the hydraulicfluid at the valve seat and to be closed by the pressure of hydraulicfluid effective against the opposite end of the valve member, arestricted passage for the admission of hydraulic fluid against saidopposite end of the valve member, means independent of the pressurevariations at the valve seat for supplying hydraulic fluid to saidrestricted passage, a throttle valve in said independent hydraulic Huidsupply, and a relief valve in said independent hydraulic fluid supply.

4. lln a hydraulic valve, the combination of a valve body having achambered interior for the passage of the hydraulic fluid, a valve seatin said valve body in the path of the hydraulic fluid, a movable valvemember to close said seat, the valve member being arranged to move toclose in the same direction as the travel of the hydraulic fluid throughthe valve seat when the valve member is in its open position, said valvemember being arranged to be opened by the pressure of the hydraulicfluid at the valve seat and to be closed by the pressure of hydraulicduid effective against the opposite end of the valve member, arestricted passage for the admission of hydraulic fluid against saidopposite end of the valve member, means independent of the pressurevariations at the valve seat for supplying hydraulic fluid to saidrestricted passage, means for cleansing the impurities from thehydraulic fluid admitted to said restricted passage, a throttle valve insaid independent hydraulic fluid supply, and a relief valve in saidindependent h draulic fluid supply.

5. n a hydraulic valve, the combination of a. valve body having achambcred interior for the passage of the hydraulic fluid, a valve seatin said valve body in the path of the hydraulic fluid, a movable valvemember to close said seat, the valve member being arranged to move toclose in the same direction as the travel of the hydraulic fluid throughthe valve seat when the valve member is in its open position, said valvemember being arranged to be opened by the pressure of the hydraulicfluid at the valve seat and to be closed by the pressure of hydraulicfluid effective against the opposite end of the valve member, arestricted passage for lthe admission of hydraulic fluid against saidopposite end of the valve member, means independent of the pressurevariations at the valve seat for supplying hydraulic fluid to saidrestricted passage, a relief valve for said independent hydraulic fluidsupply and means for varying the rate of fluid admission through saidrestricted passage.

6. In a hydraulicvalve, the combination of a valve body having achambered interior for the passage of hydraulic fluid, a valve seat insaid valve body inthe path of the hydraulic fluid, a movable valvemember to close said seat, the valve member being arranged to move toclose in the same direction as the travel of the hydraulic fluid throughthe valve seat when the valve member is in its open osition, said valvemember being arrange to be opened by the pressure of the hydraulic fluidat the valve seat and to be closed by the pressure of hydraulic fluideffective against-the opposite end of the valve member, a restrictedpassage for the admission of hydraulic fluid against said opposite endof the valve member, means independent of the pressure variations at thevalve seat for supplying hydraulic fluid to said restricted passage, arelief valve for said independent hydraulic fluid supply means forvarying the rate of fluid admission through said restricted passage, andmeans for cleansing the impurities from the hydraulic fluid supplied tosaid restricted passa e.

7. The combination with a multiple-way hydraulic valve body havingpassageways for the hydraulic fluid and valves interposed in saidpassageways, said valves being arranged to be opened by the pressures inthe corresponding passageways and to be closed by pressure effective atthe other side of said valves, of a hydraulic fluid supply, independentof the variations in pressure in the passageways of said valve body forsupplying hydraulic fluid for closing said valves, and a common controlvalve in said independent hydraulic fluid supply arranged for theselective opening of said valves.

8. The combination with a multiple-way hydraulic valve body havingpassageways for the hydraulic fluid and valves interposed in saidpassageways, said valves being arranged to be opened by the pressures inthe corresponding passageways and to be closed by pressure effective atthe other side of said valves, of a hydraulic fluid supply, independentof the variations in pressure in the passageways of said valve body, forsupplying hydraulic fluid for closing sa1d valves, a common controlvalve in said independent hydraulic fluid supply arranged for theselective opening of said valves, and means for varying the rate of saidhydraulic fluid supply.

9. The combination with a multiple-Way hydraulic valve body havingpassageways for the hydraulic fluid and valves interposed in saidpassageways, said valves being arranged to be opened by the pressures inthe corresponding passageways and to be closed by pressures effective atthe other side of said valves, of a hydraulic fluid supply, independentof the variations in pressure in the passageways of said valve body, forsupplying hydraulic fluid for closing sa1d valves, and a control valveoutside of the valve body for relieving the pressures from the lastmentioned side of the valves, said control valve being arranged lfor theselective opening of said valves.

10. The combination with a multiple-way hydraulic valve body havingpassageways f for the hydraulic fluid and valves interposed in saidpassageways, said valves being arranged to be opened by the pressures inthe corresponding passageways and to be closed by pressure effective atthe other side of said valves, of a hydraulic fluid supply, independentof the variations in ressure in the passageways of said valve bo y, forsupplying hydraulic fluid for closing sa1d valves, means for' varyingthe rate of said hydraulic fluid supply, and a control valve for theselective relief of the pressure from the last mentioned side of saidvalves.

1l. The combination of a multiple-way hydraulic valve body havingpassageways for the hydraulic fluid and valves interposed in saidpassageways, said valves being arranged to be opened by the pressures inthe corresponding passageways, of a hydraulic fluid supply, independentof the variations in pressure in the passageways of said valve body, forclosing said valves, and a control valve for the selective relief of theclosing fluid pressure to permit the valves to open.

12. The combination of a multiple-way hydraulic valve body havingpassageways for the hydraulic fluid and valves interposed in saidpasageways, said valves being arranged to be opened by the pressures inthe corresponding passageways, of a hydraulic Huid supply, independentof the variations in ressure in the passageways of said Valve ody, forclosing said valves, means for straining the liquid of said hydrauliefluid supply, and a control valve for the selective relief of theclosing pressures to permit the valves to open.

13. The combination of a multiple-way hydraulic valve body havingpassageways lo for the hydraulic fluid and valves interosed in saidpassageways,' said valvesr belng arranged to be opened by the pressuresin the corresponding passageways, of a hydraulic uid supply, independentof the variations in pressure in the valve body, for closing saidvalves, means for varying the rate of admission of said hydraulic fluidand a control valve for the selective relie of the closing pressures topermit said valves to open. l

Signed at Pittsburgh, Pennsylvania, this 12th day of October, 1927.

'CLARENCE E. POWELL.y

